Document handlers have become important features of modern copiers and scanners. Ideally, they operate at the maximum speed of the copier or scanner, feed the pages of a multipage document past an exposure position in a desired order and leave the document in its original order.
Simplex document handlers have long accomplished this objective by receiving a stack of document sheet in a supply tray face down, separating the sheets from the bottom of the stack and feeding them across an exposure position to an output tray. Succeeding sheets are fed to the top of the previously handled sheets in the output tray, maintaining the original order. If the document sheets are separated from the top of the stack in the supply means, sheet separation is simplified but the document sheets must be turned over to be put in their original order, see for example, U.S. Pat. No. 4,326,797.
Duplex document handlers which consecutively present opposite sides of a document sheet to the same exposure position must turn the document over between presentations, maintain the order and orientation in the output tray and, as much as possible keep up with the exposure capability of the equipment.
U.S. Pat. No. 3,227,444 shows a document handler using a drum to feed a single document sheet past an exposure position. The document sheet is fed off the drum into a turnaround path where its direction is reversed, the trailing edge becoming the leading edge, and the sheet is fed back around the drum to expose the other side. No output tray is shown and the input is one sheet at a time, so the problem of the orientation of the sheets in an output tray is not faced. However, this structure illustrates a problem with this type of document handler. If a stack were placed in the input position with this structure, either simplex or duplex type documents would arrive in the output tray in reversed orientation, depending upon whether the stack was separated off the top or off the bottom.
In a structure shown in IBM Technical Disclosure Bulletin, Vol. 14, No. 4, Oct. 1971, this problem is dealt with in a top separating device by feeding the document through the entire turnover mechanism one more time in the duplex mode to re-orient the sheets. This ties up the exposure portion of the machine and thereby materially slows it down.
Additional turnover mechanisms can be added to re-orient the sheets, but this adds substantially to the expense of the equipment. DISCLOSURE OF THE INVENTION
It is the object of the invention to provide a duplex document handler generally of the type described but which delivers both duplex and simplex document sheets to an output tray in desired orientation without an additional turnaround mechanism or without materially slowing up the equipment for an additional inversion.
These and other objects are accomplished by providing separate output trays for simplex and duplex which are each positioned to receive the appropriate type document sheets in correct orientation. According to a preferred embodiment, the simplex output tray is positioned opposite the exposure position from a common supply tray to provide a straight through simplex paper path. To preserve compactness the duplex output tray is located generally above the supply tray. Preferably, the duplex output tray is hinged to provide access to the supply tray.
According to a preferred embodiment, a turnover drum is located to support the document sheet in the exposure position and rotationally guides the sheet around an inverting path, back to the exposure position for exposure of the reverse side and through the inverting paths to the duplex output tray.